The Archons would be used as a "Shock and Awe" kinda unit, utilizing the freakish health and speed for cutting the enemies down while taking minimal damage but as well providing buffs for it's allies such as small aim or will buffs and at higher levels, inspiring troops to dodge. It could also gain a buff from how well the squad performs such as extra movement or increased critical chance if no-one in the squad misses for a turn. I would think that they would take longer to heal due to their bio-mechanical bodies. You should also do multiple pathways for how the archon can turn out in a similar way to the sharpshooter's gunslinger or sniper pathways, like a support leader or a predator skill trees where the predator would be a throwback to the old floaters.